Cheonggyecheon is a stream bisecting down town Seoul, South Korea. This stream has a length of 5.84 km(its trail-12.04 km long) and its greatest width is 84m. This stream is famous for restoration. It was a sewer of Seoul in the Joseon Dynasty. For half a century, industrial era after the Korean War, it had been entombed by pavement and had been a highway. After the restoration, Cheonggycheon has become an ecological park. The restoration of Cheonggyecheon took three years spending almost $400 million. Since its opening in 2005, hundreds of thousands of people have visited Cheonggyecheon with friends and family. Many interesting events have been often held at Cheonggyecheon as well.

It was originally called 'Gaecheon(Hangul:개천, Hanja:開川 ).' The Cheonggyecheon used to be a naturally formed stream before the Joseon Dynasty designated Seoul as its capital.[1] This stream caused a flood and inundated private houses in full spate. In ordinary times, it was unsanitary because of standing sewage therein. Therefore, King Taejong, the third king of the Joseon Dynasty, firstly beginned river training work by starting construction work for an open channel. After that, King Yeongjo, the 21st king of the Joseon Dynasty, conducted the overhaul of the stream in earnest by dredging the stream, building stone banks and changing a waterway. Due to this construction, the curved waterway of the stream became straight one at last. During the reign of King Sunjo and King Kojong, the overhaul of the stream was continued. There were 24 bridges over the stream(now 22 bridges).[2]

During the Japanese colonial period, it came to get called "Cheonggye" as it is called today, supposedly from 1914, when the colonialists rearranged stream names in Korea.[1] In this perion, the large-scale dredging of this stream was planned in terms of a modern urban planning by Japan but it wasn't carried out because of lack of funds. Therefore, the urban improvement project was neglected.

As a result, by Korea’s independence from Japan in 1945, the Cheonggyecheon was severely contaminated with wastes from flimsy shacks built alongside of the stream. It had a fetid smell as well. In terms of Seoul's appearance and sanitation, the then Cheonggyecheon was a serious problem. The easiest way of solving this promblem was covering over the stream with concrete. In 1958, finally, the work to cover it up with concrete started as quickly as possible by August 1958. In addition, a 5.6 km-long, 16 m-wide elevated highway was completed over the stream in August 1971 after four working years.[1]

About 40 years after covering over the stream with concrete, Seoul city had resuscitated the stream since July 2003. After $386 milion recovery project, Cheonggyecheon was born again as a haven for wildlife as well as pedestrians in September 2005